s=input("请输入字符串")
res=true
if s.isspace() is False:
    mid_01=s.lower()
    mid_02=mid_01.replace(" ","")
    if mid_02.isalnum() is False:
        print("含有非法字符，验证失败")
    else:
        begin=0
        end=len(mid_02) - 1
        while begin < end:
            if mid_02[begin]!=mid_02[end]:
                res = False
                break
            begin +=1
            end -=1
        print(res)
else:
    print(res)